About This Project

We are designing, building, and testing performance of version 2 of a stingray-inspired underwater autonomous robot. Our first prototype based on Dasyatis Americana ("southern stingray") achieved successful forward swimming. With version 2, we aim to achieve turning and ballast control, as well as rectify issues with buoyancy such that it can swim at the substrate instead of at the surface. Potential future applications include low disturbance remote sensing and environmental monitoring.

Ask the Scientists

What is the context of this research?

Stingrays are energy efficient swimmers that are capable of executing high acceleration maneuvers. They are a natural source for bioinspired design. We will design, build, and test the 2nd generation of a stingray-inspired underwater robot based on the D. Americana. Last year, as part of a capstone design course, we demonstrated a first working prototype, with four servo motors actuated flexible fiberglass fishing rods embedded in the cured silicone forming the main body. It achieved successful untethered forward swimming with a maximum velocity of 10 cm/s (~0.3 body lengths/s). A new and revised design will additionally allow for control of turning and ballast for diving/surfacing. Version 1 was developed by student group for capstone project on bioinspired design; Ditto for version 2.

What is the significance of this project?

All stingrays species are adept at using their enlarged pectoral fins to deftly maneuver and hold station in shallow waters and tight spaces, such as coral and other seabed features. This extreme maneuverability and control authority exceeds that of state-of-the-art conventional robot swimmers. In addition, stingrays are quiet swimmers; they do not stir up sand or silt as they propel themselves. One potential future application, therefore, would be for non-invasive remote sensing and environmental monitoring in marine environments. While others have previously demonstrated oscillatory ("flapping") and undulatory ("rippling") ray-based robots, to the best of our knowledge, our design is the first to incorporate an intermediate propulsion mechanism.

What are the goals of the project?

Building on our experience with the previous design, version 2 will incorporate a more streamlined central control box for higher efficiency, expanded actuation options to turn left or right, ballast control to dive or surface. In addition, we aim to achieve neutral buoyancy such that it swims near the substrate, not at the water surface. The central waterproof central chamber will be completely redesigned in CADD, then 3-D printed. New high-energy, small form factor servos will be used to fit inside the smaller central housing. The microcontroller code controlling the servos will be upgraded to turn left or right by reversing the direction of wave propagation on one side. Ballast control will be achieved by moving a weight aft or rear in automated fashion.